Boeing's 737 is indisputably the most popular and arguably the safest commercial airliner in the world. But the plane had a lethal flaw, and only after several disastrous crashes and years of painstaking investigation was the mystery of its rudder failure solved. This book tells the story of how engineers and scientists finally uncovered the defect that had been engineered into the plane. One of its novel features is that it portrays the complex interaction of different experts and opposing interests in investigating and solving the mystery of this single crash.